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.TH FMA 3M "Jul 12, 2006" "SunOS 5.11" "Mathematical Library Functions"
.SH NAME
fma, fmaf, fmal \- floating-point multiply-add
.SH SYNOPSIS
.LP
.nf
c99 [ \fIflag\fR... ] \fIfile\fR... \fB-lm\fR [ \fIlibrary\fR... ]
#include <math.h>

\fBdouble\fR \fBfma\fR(\fBdouble\fR \fIx\fR, \fBdouble\fR \fIy\fR, \fBdouble\fR \fIz\fR);
.fi

.LP
.nf
\fBfloat\fR \fBfmaf\fR(\fBfloat\fR \fIx\fR, \fBfloat\fR \fIy\fR, \fBfloat\fR \fIz\fR);
.fi

.LP
.nf
\fBlong double\fR \fBfmal\fR(\fBlong double\fR \fIx\fR, \fBlong double\fR \fIy\fR, \fBlong double\fR \fIz\fR);
.fi

.SH DESCRIPTION
.sp
.LP
These functions compute (\fIx\fR * \fIy\fR) + \fIz\fR, rounded as one ternary
operation. They compute the value (as if) to infinite precision and round once
to the result format, according to the rounding mode characterized by the value
of \fBFLT_ROUNDS\fR.
.SH RETURN VALUES
.sp
.LP
Upon successful completion, these functions return (\fIx\fR * \fIy\fR) +
\fIz\fR, rounded as one ternary operation.
.sp
.LP
If \fIx\fR or \fIy\fR are NaN, a NaN is returned.
.sp
.LP
If \fIx\fR multiplied by \fIy\fR is an exact infinity and \fIz\fR is also an
infinity but with the opposite sign, a domain error occurs and a NaN is
returned.
.sp
.LP
If one of \fIx\fR and \fIy\fR is infinite, the other is 0, and \fIz\fR is not a
NaN, a domain error occurs and a NaN is returned.
.sp
.LP
If \fIx\fR*\fIy\fR is not 0*Inf nor Inf*0 and \fIz\fR is a NaN, a NaN is
returned.
.SH ERRORS
.sp
.LP
These functions will fail if:
.sp
.ne 2
.mk
.na
\fBDomain Error\fR
.ad
.RS 16n
.rt
The value of \fIx\fR*\fIy\fR+\fIz\fR is invalid or the value \fIx\fR*\fIy\fR is
invalid.
.sp
If the integer expression (\fBmath_errhandling\fR & \fBMATH_ERREXCEPT\fR) is
non-zero, the invalid floating-point exception will be raised.
.RE

.sp
.ne 2
.mk
.na
\fBRange Error\fR
.ad
.RS 16n
.rt
The result overflows.
.sp
If the integer expression (\fBmath_errhandling\fR & \fBMATH_ERREXCEPT\fR) is
non-zero, the overflow floating-point exception will be raised.
.RE

.SH USAGE
.sp
.LP
An application wanting to check for exceptions should call
\fBfeclearexcept\fR(\fBFE_ALL_EXCEPT\fR) before calling these functions. On
return, if \fBfetestexcept\fR(\fBFE_INVALID\fR | \fBFE_DIVBYZERO\fR |
\fBFE_OVERFLOW\fR | \fBFE_UNDERFLOW\fR) is non-zero, an exception has been
raised. An application should either examine the return value or check the
floating point exception flags to detect exceptions.
.SH ATTRIBUTES
.sp
.LP
See \fBattributes\fR(7) for descriptions of the following attributes:
.sp

.sp
.TS
tab(	) box;
cw(2.75i) |cw(2.75i)
lw(2.75i) |lw(2.75i)
.
ATTRIBUTE TYPE	ATTRIBUTE VALUE
_
Interface Stability	Standard
_
MT-Level	MT-Safe
.TE

.SH SEE ALSO
.sp
.LP
.BR math.h (3HEAD),
.BR feclearexcept (3M),
.BR fetestexcept (3M),
.BR attributes (7),
.BR standards (7)
